In the largest and longest kidnapping campaign ever undertaken up to that time, Dan Mitrione, the Chief Public Safety Advisor of the American Embassy in Uruguay, was kidnapped near his home in Montevideo on July 31, 1970, by the National Liberation Movement (MLN), popularly known as the Tupamaros, the most proficient urban guerrilla organization in existence. Mitrione was seized as part of an unusual diplomatic kidnapping campaign, in which Brazilian Consul Aloysio Dias Gomide was abducted the same day, an unsuccessful attempt was subsequently made to kidnap U.S. Embassy Second Secretary Gordon Jones, and AID contract employee Claude Fly and British Ambassador Geoffery Jackson were later abducted. This kidnapping campaign represented the unfolding of a strategic operation called Plan Satan, in which the Tupamaros sought to provoke a ministerial crisis and foreign intervention, to lead ultimately to the downfall of the Uruguayan government. The specific tactical objective of the Mitrione and Dias Gomide kidnappings and the unsuccessful attempt on Jones was the liberation of some 150 Tupamaros then imprisoned or detained by the government. This constituted the largest prisoner ransom ever demanded for kidnapped diplomats. As the Uruguayan President stood fast and refused any prisoner exchange, the kidnappers executed Mitrione on August 10.